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use crate::lock::RwLock;
use crate::mapref::multiple::{RefMulti, RefMutMulti};
use crate::util;
use crate::{DashMap, HashMap};
use core::hash::{BuildHasher, Hash};
use rayon::iter::plumbing::UnindexedConsumer;
use rayon::iter::{FromParallelIterator, IntoParallelIterator, ParallelExtend, ParallelIterator};
use std::collections::hash_map::RandomState;
use std::sync::Arc;
impl<K, V, S> ParallelExtend<(K, V)> for DashMap<K, V, S>
where
K: Send + Sync + Eq + Hash,
V: Send + Sync,
S: Send + Sync + Clone + BuildHasher,
{
fn par_extend<I>(&mut self, par_iter: I)
where
I: IntoParallelIterator<Item = (K, V)>,
{
(&*self).par_extend(par_iter);
}
}
// Since we don't actually need mutability, we can implement this on a
// reference, similar to `io::Write for &File`.
impl<K, V, S> ParallelExtend<(K, V)> for &'_ DashMap<K, V, S>
where
K: Send + Sync + Eq + Hash,
V: Send + Sync,
S: Send + Sync + Clone + BuildHasher,
{
fn par_extend<I>(&mut self, par_iter: I)
where
I: IntoParallelIterator<Item = (K, V)>,
{
let &mut map = self;
par_iter.into_par_iter().for_each(move |(key, value)| {
map.insert(key, value);
});
}
}
impl<K, V, S> FromParallelIterator<(K, V)> for DashMap<K, V, S>
where
K: Send + Sync + Eq + Hash,
V: Send + Sync,
S: Send + Sync + Clone + Default + BuildHasher,
{
fn from_par_iter<I>(par_iter: I) -> Self
where
I: IntoParallelIterator<Item = (K, V)>,
{
let map = Self::default();
(&map).par_extend(par_iter);
map
}
}
// Implementation note: while the shards will iterate in parallel, we flatten
// sequentially within each shard (`flat_map_iter`), because the standard
// `HashMap` only implements `ParallelIterator` by collecting to a `Vec` first.
// There is real parallel support in the `hashbrown/rayon` feature, but we don't
// always use that map.
impl<K, V, S> IntoParallelIterator for DashMap<K, V, S>
where
K: Send + Eq + Hash,
V: Send,
S: Send + Clone + BuildHasher,
{
type Iter = OwningIter<K, V, S>;
type Item = (K, V);
fn into_par_iter(self) -> Self::Iter {
OwningIter {
shards: self.shards,
}
}
}
pub struct OwningIter<K, V, S = RandomState> {
shards: Box<[RwLock<HashMap<K, V, S>>]>,
}
impl<K, V, S> ParallelIterator for OwningIter<K, V, S>
where
K: Send + Eq + Hash,
V: Send,
S: Send + Clone + BuildHasher,
{
type Item = (K, V);
fn drive_unindexed<C>(self, consumer: C) -> C::Result
where
C: UnindexedConsumer<Self::Item>,
{
Vec::from(self.shards)
.into_par_iter()
.flat_map_iter(|shard| {
shard
.into_inner()
.into_iter()
.map(|(k, v)| (k, v.into_inner()))
})
.drive_unindexed(consumer)
}
}
// This impl also enables `IntoParallelRefIterator::par_iter`
impl<'a, K, V, S> IntoParallelIterator for &'a DashMap<K, V, S>
where
K: Send + Sync + Eq + Hash,
V: Send + Sync,
S: Send + Sync + Clone + BuildHasher,
{
type Iter = Iter<'a, K, V, S>;
type Item = RefMulti<'a, K, V, S>;
fn into_par_iter(self) -> Self::Iter {
Iter {
shards: &self.shards,
}
}
}
pub struct Iter<'a, K, V, S = RandomState> {
shards: &'a [RwLock<HashMap<K, V, S>>],
}
impl<'a, K, V, S> ParallelIterator for Iter<'a, K, V, S>
where
K: Send + Sync + Eq + Hash,
V: Send + Sync,
S: Send + Sync + Clone + BuildHasher,
{
type Item = RefMulti<'a, K, V, S>;
fn drive_unindexed<C>(self, consumer: C) -> C::Result
where
C: UnindexedConsumer<Self::Item>,
{
self.shards
.into_par_iter()
.flat_map_iter(|shard| {
let guard = shard.read();
let sref: &'a HashMap<K, V, S> = unsafe { util::change_lifetime_const(&*guard) };
let guard = Arc::new(guard);
sref.iter().map(move |(k, v)| {
let guard = Arc::clone(&guard);
unsafe { RefMulti::new(guard, k, v.get()) }
})
})
.drive_unindexed(consumer)
}
}
// This impl also enables `IntoParallelRefMutIterator::par_iter_mut`
impl<'a, K, V, S> IntoParallelIterator for &'a mut DashMap<K, V, S>
where
K: Send + Sync + Eq + Hash,
V: Send + Sync,
S: Send + Sync + Clone + BuildHasher,
{
type Iter = IterMut<'a, K, V, S>;
type Item = RefMutMulti<'a, K, V, S>;
fn into_par_iter(self) -> Self::Iter {
IterMut {
shards: &self.shards,
}
}
}
impl<'a, K, V, S> DashMap<K, V, S>
where
K: Send + Sync + Eq + Hash,
V: Send + Sync,
S: Send + Sync + Clone + BuildHasher,
{
// Unlike `IntoParallelRefMutIterator::par_iter_mut`, we only _need_ `&self`.
pub fn par_iter_mut(&self) -> IterMut<'_, K, V, S> {
IterMut {
shards: &self.shards,
}
}
}
pub struct IterMut<'a, K, V, S = RandomState> {
shards: &'a [RwLock<HashMap<K, V, S>>],
}
impl<'a, K, V, S> ParallelIterator for IterMut<'a, K, V, S>
where
K: Send + Sync + Eq + Hash,
V: Send + Sync,
S: Send + Sync + Clone + BuildHasher,
{
type Item = RefMutMulti<'a, K, V, S>;
fn drive_unindexed<C>(self, consumer: C) -> C::Result
where
C: UnindexedConsumer<Self::Item>,
{
self.shards
.into_par_iter()
.flat_map_iter(|shard| {
let mut guard = shard.write();
let sref: &'a mut HashMap<K, V, S> =
unsafe { util::change_lifetime_mut(&mut *guard) };
let guard = Arc::new(guard);
sref.iter_mut().map(move |(k, v)| {
let guard = Arc::clone(&guard);
unsafe { RefMutMulti::new(guard, k, v.get_mut()) }
})
})
.drive_unindexed(consumer)
}
}
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